1. Field of the Invention
The present invention relates to a load-driving circuit for driving loads such as motors, and more particularly, to a load-driving circuit capable of driving a plurality of loads based on a priority order endowed therewith.
2. Description of the Related Art
Disclosed in, for instance, Japanese Unexamined Patent Application Publication No. 8-105270 is a power window apparatus with plural sets of driving devices, each having a power window motor and a power window switch for driving the power window motor, in which the operation of the power window switch with the highest priority order takes precedence, and the operation of the remaining switches is invalidated, when a plurality of the power window switches operates at the same time.
The conventional power window apparatus described above is constructed with a microcomputer. Therefore, the apparatus can be driven in accordance with the predetermined order of priority given to the power window driving motors by the programs incorporated into the microcomputer. Furthermore, a control method thereof can be easily changed, thereby improving the convenience of use and scalability.
However, if two sets of driving devices are provided, a microcomputer and peripheral circuits related thereto are required in order to determine the priority order of power window switches. Therefore, employing a circuit device for endowing a priority order is costly and tends to increase the size of the power window apparatus.